Conventional liquid fabric softening compositions are typically in the form of dispersed colloidal particles of the fabric softening compound. Fabric softening compositions formed from dispersed colloidal particles generally have complex and unstable structures. Because of this inherent instability, many problems are associated with conventional fabric softening compositions such as product or viscosity instability, especially after long time storage, such that the corresponding compositions become unpourable and have inadequate dispensing and dissolving characteristics in rinse water. In addition, at all steps of the fabric softening composition manufacturing and transportation chain, such composition may be subjected to unwanted shear and shaking which may prematurely affect product stability of the products. This may especially happen when the corresponding composition is produced upon high-shear mixing or when the finished composition is transported or stored under extreme conditions such as in uneven regions. This may pose problems to the user upon usage or may affect retailers when placing products on the shelves, without mentioning any associated loss of performance for the softening products.
The afore-mentioned problems are known to be further exacerbated when the softening composition is in concentrated form, when a perfume is further incorporated, or when the composition is subjected to high temperatures. Moreover, recent liquid fabric softening compositions typically make use of quaternized ester-amines which are known to be rapidly biodegradable. Unfortunately, those softening actives are more subject to hydrolysis than conventional softening agents and hence can encounter hydrolytic stability problems upon prolonged shelf storage.
Partial solutions to these drawbacks have been provided with for example in WO 97/17419 which discloses fabric conditioning compositions comprising a softening agent, a perfume and a diester for achieving reduced instability of the softener compositions caused by perfumes and extremes conditions. U.S. Pat. No. 4,840,738 and U.S. Pat. No. 4,386,000 disclose fabric softening compositions claimed to possess desirable product stability and viscosity characteristics at both normal and elevated temperatures.
Notwithstanding the benefits and advantages associated with the disclosed fabric softening compositions, there is still a need for concentrated fabric softening compositions having improved resistance to shear as well as excellent stability and viscosity characteristics upon prolonged storage, and which overcome the drawbacks associated with the know softening compositions.
It has now been found that the above objective can be met by providing a softening composition according to the present invention.
Advantageously, the compositions according to the present invention greatly facilitate the formulation of highly concentrated and compact compositions. It is a further advantage that the compositions according to the present invention provide excellent dispensability and dispersibility properties.
Other advantages and more specific properties of the method according to the present invention will be clear after reading the following description of the invention.